Parents of students who are taking the SAT test on Saturday  or getting ready for the next one in May  know that test prep can be an expensive proposition, limited mainly to affluent families who can afford expensive private tutoring sessions. But in a deepening recession that has forced families to cut back, the test-prep industry has responded by lowering prices. And business is booming.

One of the biggest low-cost growth areas is in online tutoring, a relatively new addition to the $4 billion test prep industry. The Princeton Review's cheapest online program  which includes three weeks of access to practice tests and online office hours with a certified instructor  will set you back a mere $85, less than a quarter of what the company charges for a single hour with a flesh-and-blood tutor; enrollment in its online offerings grew 15% in 2008. Over at Academic Approach, online programs are also enjoying double-digit growth. They're more expensive  $499.99 for 45 instructional videos and over 375 lessons  but still a bargain compared to $100-to-$200 an hour the company charges for in-person tutoring at its bricks-and-mortar centers in Chicago, Boston, and New York. Another not-so-surprising sign of the times: for $99 a month, TutorVista will set you up with an online tutor in Bangalore. (See pictures of the college dorm's evolution.)

Test prep teachers acknowledge that giving up the face-to-face mentoring aspect of tutoring could have a downside, namely that there's often no one cracking the whip to force kids to study. But for many students, scheduling cyber tutoring is more manageable than a marathon weekend session offline. Quinn McMahon, 18, a senior at the Thacher School in Ojai, Calif., for example, squeezed in an hour per week of online ACT prep this fall  along with supplementary phone calls to an Academic Approach tutor  in between football practice and studying for his four Advanced Placement courses. "I don't really have time to meet for long periods of time with someone," he says. "If I had a free period, I could just set it up right then, within five minutes."

And, of course, the price is right, particularly for the suddenly cash-strapped families who in recent years coughed up extravagant sums for private tutoring. Laura Wilson, founder of WilsonDailyPrep, based in wealthy Chappaqua, N.Y., says she regularly gets calls from parents who had signed their children up for private tutoring but are now hoping to scale back. Many are choosing to fill in the gaps through the online program Wilson launched in October, which already boasts 470 students. Parents are also turning to Academic Approach, which has ramped up its online program within the last year: "They're coming back for Child No. 2 and now saying, rather than work with that slightly more expensive, one-on-one tutor, they would like to try the online situation now," says CEO Matthew Pietrafetta. (See TIME's special report on paying for college.)

In addition to growing their online presence, test prep programs are expanding into an often subsidized arena: tutoring by public and private schools. While not a new idea, these in-school programs are increasingly appealing in this economy, tutors say. The Princeton Review is in talks with five states about integrating SAT or ACT prep into all of their districts. Some schools help knock 20% to 30% off students' fees by offering use of their classrooms at no charge to the test prep company. Other districts pick up the entire tab of the Princeton Review program, offering it to students as part of their regular curriculum.

It's not just wealthy districts, either. Kaplan has started prep programs in economically troubled cities like Detroit and Stockton, Calif., where the courses are school-funded and free for students. PrepMe is working with the state of Maine as well as inner city charter schools across the Midwest, with full funding from philanthropists or the schools themselves. Aside from partnerships with high schools in the wealthy New York suburbs of Brewster and Harrison, WilsonDailyPrep also recently signed on to offer discounted online programs at Riverside High School in Yonkers, N.Y., a city where a quarter of people under 18 live below the poverty line, and Columbus High in the Bronx, where students pass through metal detectors on the way to class. "There's a huge priority among educators and private and public schools to be able to get those services to those students who need it most," says Pietrafetta, who is spearheading partnerships between Academic Approach and schools in Chicago, Boston, and New York. "The move is to make it equitable, accessible to all, so it's not just a property of the rich."